Sheet feed apparatus

ABSTRACT

Sheet feed apparatus comprising a frame, a tray for supporting a stack of sheets adapted to be fed along a predetermined path, the tray mounted for pivotable movement on an axis a direction away from the direction in which feed is to be affected, a cam member operatively engageable with the lower portion of the tray to continually pivot the tray in an upward direction on the high rise portion of the cam and then return the tray to its original position upon a rotation of the cam to the low rise portion, drive means for operatively rotating the cam member in intermittent fashion upon receipt of discrete electrical signals, and control means associated with the stack for actuating the drive means when the top of the stack falls below a predetermined plane until the sheets have been fed.

United States Patent Wagner [54] SHEET FEED APPARATUS [72] Inventor:John W. Wagner, Penfield, NY.

[73] Assignee: Xerox Corporation, Stamford, Conn.

[22] Filed: July 13, 1970 [21] Appl. No.: 54,140

[52] u.s.cn. ..27l/62,271/39 51] lnt.Cl. ..B65hl/18,B65h3/06 [58] FieldoiSearch ..271/62, 39, 61, 30, 28, 24, 271/22 [56] References CitedUNITED STATES PATENTS 3,237,935 3/1966 3,265,383 8/1966 3,360,25912/1967 3,067,885 12/1962 2,902,278 9/1959 3,025,052 3/1962 Gutteling..271/28 FOREIGN PATENTS OR APPLICATIONS 1,168,202 10/1969 Great Britain..271/39 [15] 3,655,183 [4 1 Apr. 11, 1972 Primary Examiner-JosephWegbreit Assistant Examiner-Bruce H. Stoner, Jr.

Attorney-James J. Ralabate, Norman E. Schrader and Melvin ein. a

[ ABSTRACT Sheet feed apparatus comprising a frame, a tray forsupporting a stack of sheets adapted to be fed along a predeterminedpath, the tray mounted for pivotable movement on an axis a directionaway from the direction in which feed is to be affected, a cam memberoperatively engageable with the lower portion of the tray to continuallypivot the tray in an upward direction on the high rise portion of thecam and then return the tray to its original position upon a rotation ofthe cam to the low rise portion, drive means for operatively rotatingthe cam memberin intermittent fashion upon receipt of discreteelectrical signals, and control means associated with the stack foractuating the drive means when the top of the stack falls below apredetermined plane until the sheets have been fed.

me insl'fim.

CONTROL LOGIC Patented April 11, 1972 INVENTOR JOHN w. WAGNER BY QATTORNEY SHEET FEED APPARATUS This invention relates to improvements insheet feeding devices and particularly to an improved stack advancingmechanism.

It is commonly known to feed sheets from the top of a stack whichnormally requires an elevator to raise the stack to a constant level oralternatively a feeder which adjusts to different stack heights. Thistype of arrangement has placed undue restraints on some machineconfigurations as are used, for example, in the copying field.

It is an object of the present invention to improve sheet feedapparatus.

It is another object of the present invention to maintain the level of astack of sheets to be fed in a manner more simple than heretofore.

It is still another object of the present invention to enable thefeeding of a stack of sheets without complicated elevating mechanisms orassociated equipment.

It is still another object of the present invention to feed sheetmaterial without elevating feed rolls in the sheet material path.

The foregoing objects as well as others will become more apparent withthe following description which is to be read in conjunction with theFlGURE showing the apparatus of the present invention.

The sheet feeding mechanism of the invention includes a nudger roll 18adapted to feed the top sheet of a stack 19 of sheets on a tray 20 tofeed rollers 22 and 24. As the sheets are fed into the rollers 22 and24, one or more guide members 25 serve to guide the sheets into the nipof the rollers as well as ensure proper alignment of the leading edge ofthe stack of sheets. In feeding sheets from the stack one at a time, asthe topmost sheet is advanced forward, the movement of the topmost sheetwill tend to advance the second sheet also. In order to ensureseparation of the topmost sheet from the stack,

roller 24 functions as a rejector roll through a slip clutch operatingoff the drive of the gearing from the positively driven roll 22.

In accordance with the present invention as sheets are fed from the topof the stack, the tray 20 is elevated by pivoting on an axis by means ofa control mechanism as will now be described. Situated on the top of thestack in contact with the topmost sheet is a paper level sensingmechanism comprising a wheel 32 secured to an arm 34 which is pivotallymounted to a switch 36. As the sheets are fed, wheel 32 through gravitywill try to follow the level of the sheets and such action will causeswitch 36 to be energized and provide a signal to a control motor 38through a control logic 58. Motor 38 provides the drive input to anelevating mechanism 39 which will now be described. The elevatingmechanism 39 comprises a worm 40 which meshes with a worm wheel 42which, in turn, drives a shaft 44 received by the wheel which shaft ismounted for rotation on suitable bearings. Mounted on the shaft 44 is anelevating cam member 50 which is eccentric in shape and serves to urgethe lower surface of the tray member 20 upwardly under control of thesheet level sensing switch 36 thereby causing tray member 20 to pivotabout the axis 30. Upon tray member 20 reaching its uppermost position,a switch 56 similar to switch 36 is actuated which is coupled to motor38 through control logic 58. Control logic 58 serves to energize themotor until tray member 20 is returned to its original position throughthe action of a spring 60. At this time, a limit switch 62 is actuatedto signal control logic 58 to deenergize motor 38.

It will now be appreciated that as the sheets from the-stack are fed,the tray member continues to maintain the topmost sheet into contactwith the feed rolls 18 due to the action of the level sensing controland elevating mechanism just described. In this manner, the level of thestack is maintained at a predetermined height which enables separationand advancement of a single sheet from the stack without the re uirementof elevating feed rolls and the lilge.

t will be appreciated hat the tray mechanism of the present invention isa unique way for feeding a stack of sheets. I! does not requirecomplicated drives or sensing mechanisms which are not only costly buttend to complicate and restrict the design of sheet feed apparatus. Itwill be further appreciated that the device of the invention can be usedin many applications and is especially useful in the copying art wheresheet feed mechanisms which are simple and reliable are in great demand.

What is claimed is:

1. An improved sheet feed apparatus comprising a frame,

a tray for supporting a stack of sheets adapted to be fed along apredetermined path,

said tray being mounted for pivotable movement on an axis in an upwarddirection,

a cam member operatively engageable with the lower portion of said trayto pivot said tray in an upward direction during operation on a highrise portion of said cam and then return said tray to its originalposition upon actuation of said cam to a low rise portion thereof,

drive means including a motor connected to a worm member driving a wormwheel operatively rotating said cam member in response to discreteelectrical signals,

control means associated with said stack including first circuit meansoperative in response to the level of said stack for energizing saidmotor in intermittent fashion for actuating said drive means when thetop of said stack falls below a predetermined plane until said sheetshave been fed from said tray and second circuit means operative whensaid tray reaches its uppermost position for continuously energizingsaid motor to return said tray to its starting position, and

a spring member connected to said frame and the bottom of said tray tofacilitate the return of said tray to its starting position.

1. An improved sheet feed apparatus comprising a frame, a tray forsupporting a stack of sheets adapted to be fed along a predeterminedpath, said tray being mounted for pivotable movement on an axis in anupward direction, a cam member operatively engageable with the lowerportion of said tray to pivot said tray in an upward direction duringoperation on a high rise portion of said cam and then return said trayto its original position upon actuation of said cam to a low riseportion thereof, drive means including a motor connected to a wormmember driving a worm wheel operatively rotating said cam member inresponse to discrete electrical signals, control means associated withsaid stack including first circuit means operative in response to thelevel of said stack for energizing said motor in intermittent fashionfor actuating said drive means when the top of said stack falls below apredetermined plane until said sheets have been fed from said tray andsecond circuit means operative when said tray reaches its uppermostposition for continuously energizing said motor to return said tray toits starting position, and a spring member connected to said frame andthe bottom of said tray to facilitate the return of said tray to itsstarting position.